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1971 Datsun 521


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Yes I put it on series to check but apparently it lights up with basically touching any metal part on the truck. It lights up touching the front grill the motor or any engine bay part. So now I’m just confused. The battery positive is connected to the starter then from the starter it connects to the alternator positive. Starter doesn’t have a ground strap but the alternator is grounded from the back to the frame of the truck. The negative of the battery is grounded to the engine block

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It's a continuity tester.  It has it's own power source.  You're basically just proving that those things are grounds.  If you are looking for a draw, you need a basic test light or an amp meter that you hook in series between the battery positive post and the positive terminal, which will then give you a reading if current is being drawn.  At that point you start disconnecting components until the light or reading goes of, narrowing down what is causing the draw.

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so you have your test light minus side battery clipped and the pointy to the engine  and or body your getting your light to come on is weird.


Does this truck have other grounds form the  minus battery to the chassis. Most newer car will have a strap or thick wire



disconnect the pos battery and then the light should go out.  There has got to be a relay or something  sticking (contacks)to Ground.



what is weird is the battery Post is not even grounded  and your test light is comes on?


You actually have a test light or as this is matt a continoity test which it lights up when its shorted.



You want a test light (means it a light bulb in there.

a countinoity test has a batty in there

Edited by banzai510(hainz)
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My minus is grounded to my engine block and also has my electric fans and alternator grounded to it as well. Well alternator is has two ground cables one from the battery and the other that goes in to the old 521 wiring from the original alternator from the l16

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Ok I got confused a sec. you putting the minus side battery post and other pointy end of test light  to ground of motor or chassis  is the same as in series with the black cable you just bypassing that.

If a battery drain your light will be on. as it shows


so your saying when you disconnect the sense on the alt the test light goes out?


Edited by banzai510(hainz)
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when you converted this to IR alternator you have the 2 jumpers acress where the old VR used to go?


be honest on the newer motor sa I dont know if there is a slight draw anyways. I know the old Datsun it was EZ just pull the fuses till the light when out to find the circut that is bad. then put the fuse back in then disconnected single items in that circut till light when out. then you found the actual short

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6 minutes ago, Zonargx said:

Battery negative to positive or in this case any metal in the truck it lights up

yes you have a short as your completeing the circut and test light is ON


 you can disconnect the main fuses first as i mentioned to find the circut its on.but fuse back in and then disconnect itemas from the circut.

since I see alot of red wires around also maybe fused or not Im guessing.

you said you swapped the altenator already.  you say sense line. I dont know exactly how that works right now

Edited by banzai510(hainz)
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I disconnect every single fuse and light is still on. Only other thing connected to the positive is my amp audio amp so I disconnect it and still on. Other thing connected is the starter and alternator. I tried just connecting the starter and removing the cable for the alternator positive and the light goes off but once I plugged the alternator positive back on it light up again. I then decided to unplug the two wires from the alternator plug and only when the sense is off the light goes off

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